Add common crate to access env variables

In the future, we should use a proper secret store (not just env variables).
This lets us update one block of code and not n in the future.

processor/src/main.rs

@@ -1,5 +1,4 @@
 use std::{
-  env,
   time::Duration,
   collections::{VecDeque, HashMap},
 };
@@ -25,6 +24,8 @@ use serai_client::{
 
 use messages::{SubstrateContext, CoordinatorMessage, ProcessorMessage};
 
+use serai_env as env;
+
 mod plan;
 pub use plan::*;